HYDROELECTRIC POWER GENERATION BASIC INFORMATION AND TUTORIALS

Hydroelectric power generation involves
the storage of a hydraulic fluid, normally water, conversion of the
hydraulic energy of the fluid into mechanical energy in a hydraulic
turbine, and conversion of the mechanical energy to electrical energy
in an electric generator.

The first hydroelectric power plants
came into service in the 1880s and now comprise approximately 22%
(660 GW) of the world’s installed generation capacity of 3000 GW
(Electric Power Research Institute, 1999).

Hydroelectricity is an important source
of renewable energy and provides significant flexibility in base
loading, peaking, and energy storage applications.

While initial capital costs are high,
the inherent simplicity of hydroelectric plants, coupled with their
low operating and maintenance costs, long service life, and high
reliability, make them a very cost effective and flexible source of
electricity generation.

Especially valuable is their operating
characteristic of fast response for start-up, loading, unloading, and
following of system load variations. Other useful features include
their ability to start without the availability of power system
voltage (“black start capability”), ability to transfer rapidly
from generation mode to synchronous condenser mode, and pumped
storage application.

Hydroelectric units have been installed
in capacities ranging from a few kilowatts to nearly 1 GW. Multi-unit
plant sizes range from a few kilowatts to a maximum of 18 GW.

Planning of Hydroelectric Facilities

Siting

Hydroelectric plants are located in
geographic areas where they will make economic use of hydraulic
energy sources. Hydraulic energy is available wherever there is a
flow of liquid and head. Head represents potential energy and is the
vertical distance through which the fluid falls in the energy
conversion process.

The majority of sites utilize the head
developed by fresh water; however, other liquids such as salt water
and treated sewage have been utilized. The siting of a prospective
hydroelectric plant requires careful evaluation of technical,
economic, environmental, and social factors.

A significant portion of the project
cost may be required for mitigation of environmental effects on fish
and wildlife and re location of infrastructure and population from
flood plains.

Hydroelectric Plant Schemes

There are three main types of
hydroelectric plant arrangements, classified according to the method
of controlling the hydraulic flow at the site:

1. Run-of-the-river plants, having
small amounts of water storage and thus little control of the flow
through the plant.

2. Storage plants, having the ability
to store water and thus control the flow through the plant on a daily
or seasonal basis.

3. Pumped storage plants, in which the
direction of rotation of the turbines is reversed during offpeak
hours, pumping water from a lower reservoir to an upper reservoir,
thus “storing energy” for later production of electricity during
peak hours.